SPECIAL ITEMS SPECIAL ITEMS - MERGER-RELATED COSTS (Details) - USD ($) $ in Millions	12 Months Ended	49 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Merger-related Costs [Line Items]
Contracted services	$ 181	$ 289	$ 306
Special items—merger-related costs	6	44	87	$ 370
Virgin America Inc. [Member]
Merger-related Costs [Line Items]
Contracted services	5	18	45
Severance Costs	0	15	13
Legal Fees	1	1	1
Business Acquisition, Transaction Costs	0	10	28
Special items—merger-related costs	$ 6	$ 44	$ 87

[Line Items] for Merger-related Costs [Table]

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Other merger-related costs

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- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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-Section 25
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The amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to resolved, pending or threatened litigation, including arbitration and mediation proceedings.

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-Section S99
-Paragraph 2
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Professional and contract service expense includes cost reimbursements for support services related to contracted projects, outsourced management, technical and staff support.

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Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

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